*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
a{
    text-decoration: none;
}
ul{
    list-style: none;
}
input{
    outline: none;
    border: none;
}
body{
    width: 100%;
    background-color: #f5f5f5;
    position: relative;
}
/*清除浮动*/
.clearfix::before,
.clearfix::after{
    content: "";
    display: block;
    height: 0;
    line-height: 0px;
    clear: both;
    visibility: hidden;
}